/src/haproxy/src/http_ext.c

Source
/*
 * HTTP extensions logic and helpers
 *
 * Copyright 2022 HAProxy Technologies
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <haproxy/sample.h>
#include <haproxy/http_htx.h>
#include <haproxy/http_ext.h>
#include <haproxy/chunk.h>
#include <haproxy/stream.h>
#include <haproxy/proxy.h>
#include <haproxy/sc_strm.h>
#include <haproxy/obj_type.h>
#include <haproxy/cfgparse.h>
#include <haproxy/arg.h>
#include <haproxy/initcall.h>
#include <haproxy/tools.h>

/*
 * =========== ANALYZE ===========
 * below are http process/ana helpers
 */

/* checks if <input> contains rfc7239 compliant port
 * Returns 1 for success and 0 for failure
 * if <port> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_port(struct ist *input, uint16_t *port)
{
  char *start = istptr(*input);
  uint32_t port_cast = 0;
  int it = 0;

  /* strtol does not support non-null terminated str,
   * we extract port ourselves
   */
  while (it < istlen(*input) &&
         isdigit((unsigned char)start[it])) {
    port_cast = (port_cast * 10) + (start[it] - '0');
    if (port_cast > 65535)
      return 0; /* invalid port */
    it += 1;
  }
  if (!port_cast)
    return 0; /* invalid port */
  /* ok */
  if (port)
    *port = (uint16_t)port_cast;
  *input = istadv(*input, it);
  return 1;
}

/* check if char is a valid obfuscated identifier char
 * (according to 7239 RFC)
 * Returns non zero value for valid char
 */
static inline int http_7239_valid_obfsc(char c)
{
  return (isalnum((unsigned char)c) ||
                (c == '.' || c == '-' || c == '_'));
}

/* checks if <input> contains rfc7239 compliant obfuscated identifier
 * Returns 1 for success and 0 for failure
 * if <obfs> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_obfs(struct ist *input, struct ist *obfs)
{
  int it = 0;

  if (obfs)
    obfs->ptr = input->ptr;

  while (it < istlen(*input) && istptr(*input)[it] != ';') {
    if (!http_7239_valid_obfsc(istptr(*input)[it]))
      break; /* end of obfs token */
    it += 1;
  }
  if (obfs)
    obfs->len = it;
  *input = istadv(*input, it);
  return !!it;
}

/* checks if <input> contains rfc7239 compliant IPV4 address
 * Returns 1 for success and 0 for failure
 * if <ip> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_ipv4(struct ist *input, struct in_addr *ip)
{
  char ip4[INET_ADDRSTRLEN];
  unsigned char buf[sizeof(struct in_addr)];
  void *dst = buf;
  int it = 0;

  if (ip)
    dst = ip;

  /* extract ipv4 addr */
  while (it < istlen(*input) && it < (sizeof(ip4) - 1)) {
    if (!isdigit((unsigned char)istptr(*input)[it]) &&
        istptr(*input)[it] != '.')
      break; /* no more ip4 char */
    ip4[it] = istptr(*input)[it];
    it += 1;
  }
  ip4[it] = 0;
  if (inet_pton(AF_INET, ip4, dst) != 1)
    return 0; /* invalid ip4 addr */
  /* ok */
  *input = istadv(*input, it);
  return 1;
}

/* checks if <input> contains rfc7239 compliant IPV6 address
 *    assuming input.len >= 1 and first char is '['
 * Returns 1 for success and 0 for failure
 * if <ip> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_ipv6(struct ist *input, struct in6_addr *ip)
{
  char ip6[INET6_ADDRSTRLEN];
  unsigned char buf[sizeof(struct in6_addr)];
  void *dst = buf;
  int it = 0;

  if (ip)
    dst = ip;

  *input = istnext(*input); /* skip '[' leading char */
  /* extract ipv6 addr */
  while (it < istlen(*input) &&
               it < (sizeof(ip6) - 1)) {
    if (!isalnum((unsigned char)istptr(*input)[it]) &&
        istptr(*input)[it] != ':')
      break; /* no more ip6 char */
    ip6[it] = istptr(*input)[it];
    it += 1;
  }
  ip6[it] = 0;
  if ((istlen(*input)-it) < 1 || istptr(*input)[it] != ']')
    return 0; /* missing ending "]" char */
  it += 1;
  if (inet_pton(AF_INET6, ip6, dst) != 1)
    return 0; /* invalid ip6 addr */
  /* ok */
  *input = istadv(*input, it);
  return 1;
}

/* checks if <input> contains rfc7239 compliant host
 * <quoted> is used to determine if the current input is being extracted
 * from a quoted (non zero) or unquoted (zero) token, as the parsing rules
 * differ whether the input is quoted or not according to the rfc.
 * Returns 1 for success and 0 for failure
 * if <host> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_host(struct ist *input, struct ist *host, int quoted)
{
  if (istlen(*input) < 1)
    return 0; /* invalid input */

  if (host)
    host->ptr = input->ptr;

  if (quoted && *istptr(*input) == '[') {
    /* raw ipv6 address */
    if (!http_7239_extract_ipv6(input, NULL))
      return 0; /* invalid addr */
  }
  else {
    /* ipv4 or dns */
    while (istlen(*input)) {
      if (!isalnum((unsigned char)*istptr(*input)) &&
          *istptr(*input) != '.')
        break; /* end of hostname token */
      *input = istnext(*input);
    }
  }
  if (istlen(*input) < 1 || *istptr(*input) != ':') {
    goto out; /* no optional port provided */
  }
  if (!quoted)
    return 0; /* not supported */
  *input = istnext(*input); /* skip ':' */
  /* validate port */
  if (!http_7239_extract_port(input, NULL))
    return 0; /* invalid port */
 out:
  if (host)
    host->len = (input->ptr - host->ptr);
  return 1;
}

/* checks if <input> contains rfc7239 compliant nodename
 * <quoted> is used to determine if the current input is being extracted
 * from a quoted (non zero) or unquoted (zero) token, as the parsing rules
 * differ whether the input is quoted or not according to the rfc.
 * Returns 1 for success and 0 for failure
 * if <nodename> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_nodename(struct ist *input, struct forwarded_header_nodename *nodename, int quoted)
{
  if (istlen(*input) < 1)
    return 0; /* invalid input */
  if (*istptr(*input) == '_') {
    struct ist *obfs = NULL;

    /* obfuscated nodename */
    *input = istnext(*input); /* skip '_' */
    if (nodename) {
      nodename->type = FORWARDED_HEADER_OBFS;
      obfs = &nodename->obfs;
    }
    if (!http_7239_extract_obfs(input, obfs))
      return 0; /* invalid obfs */
  } else if (*istptr(*input) == 'u') {
    /* "unknown" nodename? */
    if (istlen(*input) < 7 ||
        strncmp("unknown", istptr(*input), 7))
      return 0; /* syntax error */
    *input = istadv(*input, 7); /* skip "unknown" */
    if (nodename)
      nodename->type = FORWARDED_HEADER_UNK;
  } else if (quoted && *istptr(*input) == '[') {
    struct in6_addr *ip6 = NULL;

    /* ipv6 address */
    if (nodename) {
      struct sockaddr_in6 *addr = (void *)&nodename->ip;

      ip6 = &addr->sin6_addr;
      addr->sin6_family = AF_INET6;
      nodename->type = FORWARDED_HEADER_IP;
    }
    if (!http_7239_extract_ipv6(input, ip6))
      return 0; /* invalid ip6 */
  } else if (*istptr(*input)) {
    struct in_addr *ip = NULL;

    /* ipv4 address */
    if (nodename) {
      struct sockaddr_in *addr = (void *)&nodename->ip;

      ip = &addr->sin_addr;
      addr->sin_family = AF_INET;
      nodename->type = FORWARDED_HEADER_IP;
    }
    if (!http_7239_extract_ipv4(input, ip))
      return 0; /* invalid ip */
  } else
    return 0; /* unexpected char */

  /* ok */
  return 1;
}

/* checks if <input> contains rfc7239 compliant nodeport
 * <quoted> is used to determine if the current input is being extracted
 * from a quoted (non zero) or unquoted (zero) token, as the parsing rules
 * differ whether the input is quoted or not according to the rfc.
 * Returns 1 for success and 0 for failure
 * if <nodeport> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_nodeport(struct ist *input, struct forwarded_header_nodeport *nodeport)
{
  if (*istptr(*input) == '_') {
    struct ist *obfs = NULL;

    /* obfuscated nodeport */
    *input = istnext(*input); /* skip '_' */
    if (nodeport) {
      nodeport->type = FORWARDED_HEADER_OBFS;
      obfs = &nodeport->obfs;
    }
    if (!http_7239_extract_obfs(input, obfs))
      return 0; /* invalid obfs */
  } else {
    uint16_t *port = NULL;

    /* normal port */
    if (nodeport) {
      nodeport->type = FORWARDED_HEADER_PORT;
      port = &nodeport->port;
    }
    if (!http_7239_extract_port(input, port))
      return 0; /* invalid port */
  }
  /* ok */
  return 1;
}

/* checks if <input> contains rfc7239 compliant node (nodename:nodeport token)
 * <quoted> is used to determine if the current input is being extracted
 * from a quoted (non zero) or unquoted (zero) token, as the parsing rules
 * differ whether the input is quoted or not according to the rfc.
 * Returns 1 for success and 0 for failure
 * if <node> is not NULL, it will be set to the extracted value contained
 * in <input>
 * <input> will be consumed accordingly (parsed/extracted characters are
 * removed from <input>)
 */
static inline int http_7239_extract_node(struct ist *input, struct forwarded_header_node *node, int quoted)
{
  struct forwarded_header_nodename *nodename = NULL;
  struct forwarded_header_nodeport *nodeport = NULL;

  if (node) {
    nodename = &node->nodename;
    nodeport = &node->nodeport;
    node->raw.ptr = input->ptr;
  }
  if (!http_7239_extract_nodename(input, nodename, quoted))
    return 0; /* invalid nodename */
  if (istlen(*input) < 1 || *istptr(*input) != ':') {
    if (node)
      node->nodeport.type = FORWARDED_HEADER_UNK;
    goto out; /* no optional port provided */
  }
  if (!quoted)
    return 0; /* not supported */
  *input = istnext(*input);
  if (!http_7239_extract_nodeport(input, nodeport))
    return 0; /* invalid nodeport */
 out:
  /* ok */
  if (node)
    node->raw.len = input->ptr - node->raw.ptr;
  return 1;
}

static inline int _forwarded_header_save_ctx(struct forwarded_header_ctx *ctx, int current_step, int required_steps)
{
  return (ctx && (current_step & required_steps));
}

static inline void _forwarded_header_quote_expected(struct ist *hdr, uint8_t *quoted)
{
  if (istlen(*hdr) > 0 && *istptr(*hdr) == '"') {
    *quoted = 1;
    /* node is quoted, we must find corresponding
     * ending quote at the end of the token
     */
    *hdr = istnext(*hdr); /* skip quote */
  }
}

/* checks if current header <hdr> is RFC 7239 compliant and can be "trusted".
 * function will stop parsing as soon as every <required_steps> have
 * been validated or error is encountered.
 * Provide FORWARDED_HEADER_ALL for a full header validating spectrum.
 * You may provide limited scope to perform quick searches on specific attributes
 * If <ctx> is provided (not NULL), parsed attributes will be stored according to
 * their types, allowing you to extract some useful information from the header.
 * Returns 0 on failure and <validated_steps> bitfield on success.
 */
int http_validate_7239_header(struct ist hdr, int required_steps, struct forwarded_header_ctx *ctx)
{
  int validated_steps = 0;
  int current_step = 0;
  uint8_t first = 1;
  uint8_t quoted = 0;

  while (istlen(hdr) && (required_steps & ~validated_steps)) {
    if (!first) {
      if (*istptr(hdr) == ';')
        hdr = istnext(hdr); /* skip ';' */
      else
        goto not_ok; /* unexpected char */
    }
    else
      first = 0;

    if (!(validated_steps & FORWARDED_HEADER_FOR) && istlen(hdr) > 4 &&
                    strncmp("for=", istptr(hdr), 4) == 0) {
      struct forwarded_header_node *node = NULL;

      /* for parameter */
      current_step = FORWARDED_HEADER_FOR;
      hdr = istadv(hdr, 4); /* skip "for=" */
      _forwarded_header_quote_expected(&hdr, &quoted);
      if (_forwarded_header_save_ctx(ctx, current_step, required_steps))
        node = &ctx->nfor;
      /* validate node */
      if (!http_7239_extract_node(&hdr, node, quoted))
        goto not_ok; /* invalid node */
    }
    else if (!(validated_steps & FORWARDED_HEADER_BY) && istlen(hdr) > 3 &&
                         strncmp("by=", istptr(hdr), 3) == 0) {
      struct forwarded_header_node *node = NULL;

      /* by parameter */
      current_step = FORWARDED_HEADER_BY;
      hdr = istadv(hdr, 3); /* skip "by=" */
      _forwarded_header_quote_expected(&hdr, &quoted);
      if (_forwarded_header_save_ctx(ctx, current_step, required_steps))
        node = &ctx->nby;
      /* validate node */
      if (!http_7239_extract_node(&hdr, node, quoted))
        goto not_ok; /* invalid node */
    }
    else if (!(validated_steps & FORWARDED_HEADER_HOST) && istlen(hdr) > 5 &&
                         strncmp("host=", istptr(hdr), 5) == 0) {
      struct ist *host = NULL;

      /* host parameter */
      current_step = FORWARDED_HEADER_HOST;
      hdr = istadv(hdr, 5); /* skip "host=" */
      _forwarded_header_quote_expected(&hdr, &quoted);
      if (_forwarded_header_save_ctx(ctx, current_step, required_steps))
        host = &ctx->host;
      /* validate host */
      if (!http_7239_extract_host(&hdr, host, quoted))
        goto not_ok; /* invalid host */
    }
    else if (!(validated_steps & FORWARDED_HEADER_PROTO) && istlen(hdr) > 6 &&
                         strncmp("proto=", istptr(hdr), 6) == 0) {
      /* proto parameter */
      current_step = FORWARDED_HEADER_PROTO;
      hdr = istadv(hdr, 6); /* skip "proto=" */
      /* validate proto (only common used http|https are supported for now) */
      if (istlen(hdr) < 4 || strncmp("http", istptr(hdr), 4))
        goto not_ok;
      hdr = istadv(hdr, 4); /* skip "http" */
      if (istlen(hdr) && *istptr(hdr) == 's') {
        hdr = istnext(hdr);
        if (_forwarded_header_save_ctx(ctx, current_step, required_steps))
          ctx->proto = FORWARDED_HEADER_HTTPS;
      } else if (_forwarded_header_save_ctx(ctx, current_step, required_steps))
        ctx->proto = FORWARDED_HEADER_HTTP;
      /* rfc allows for potential proto quoting, but we don't support
       * it: it is not common usage
       */
    }
    else {
      /* not supported
       * rfc allows for upcoming extensions
       * but obviously, we can't trust them
       * as they are not yet standardized
       */

      goto not_ok;
    }
    /* quote check */
    if (quoted) {
      if (istlen(hdr) < 1 || *istptr(hdr) != '"') {
        /* matching ending quote not found */
        goto not_ok;
      }
      hdr = istnext(hdr); /* skip ending quote */
      quoted = 0; /* reset */
    }
    validated_steps |= current_step;
  }

  return validated_steps;

 not_ok:
  return 0;
}

static inline void _7239_print_ip6(struct buffer *out, struct in6_addr *ip6_addr, int quoted)
{
  char pn[INET6_ADDRSTRLEN];

  inet_ntop(AF_INET6,
      ip6_addr,
      pn, sizeof(pn));
  if (!quoted)
    chunk_appendf(out, "\""); /* explicit quoting required for ipv6 */
  chunk_appendf(out, "[%s]", pn);
}

static inline void http_build_7239_header_nodename(struct buffer *out,
                                                   struct stream *s, struct proxy *curproxy,
                                                   const struct sockaddr_storage *addr,
                                                   struct http_ext_7239_forby *forby)
{
  struct in6_addr *ip6_addr;
  int quoted = !!forby->np_mode;

  if (forby->nn_mode == HTTP_7239_FORBY_ORIG) {
    if (addr && addr->ss_family == AF_INET) {
      unsigned char *pn = (unsigned char *)&((struct sockaddr_in *)addr)->sin_addr;

      chunk_appendf(out, "%d.%d.%d.%d", pn[0], pn[1], pn[2], pn[3]);
    }
    else if (addr && addr->ss_family == AF_INET6) {
      ip6_addr = &((struct sockaddr_in6 *)addr)->sin6_addr;
      _7239_print_ip6(out, ip6_addr, quoted);
    }
    /* else: not supported */
  }
  else if (forby->nn_mode == HTTP_7239_FORBY_SMP && forby->nn_expr) {
    struct sample *smp;

    smp = sample_process(curproxy, s->sess, s,
        SMP_OPT_DIR_REQ | SMP_OPT_FINAL, forby->nn_expr, NULL);

    if (smp) {
      if (smp->data.type == SMP_T_IPV6) {
        /* smp is valid IP6, print with RFC compliant output */
        ip6_addr = &smp->data.u.ipv6;
        _7239_print_ip6(out, ip6_addr, quoted);
      }
      else if (sample_casts[smp->data.type][SMP_T_STR] &&
         sample_casts[smp->data.type][SMP_T_STR](smp)) {
        struct ist validate_n = ist2(smp->data.u.str.area, smp->data.u.str.data);
        struct ist validate_o = ist2(smp->data.u.str.area, smp->data.u.str.data);
        struct forwarded_header_nodename nodename;

        /* validate nodename */
        if (http_7239_extract_nodename(&validate_n, &nodename, 1) &&
            !istlen(validate_n)) {
          if (nodename.type == FORWARDED_HEADER_IP &&
              nodename.ip.ss_family == AF_INET6) {
            /* special care needed for valid ip6 nodename (quoting) */
            ip6_addr = &((struct sockaddr_in6 *)&nodename.ip)->sin6_addr;
            _7239_print_ip6(out, ip6_addr, quoted);
          } else {
            /* no special care needed, input is already rfc compliant,
             * just print as regular non quoted string
             */
            chunk_cat(out, &smp->data.u.str);
          }
        }
        else if (http_7239_extract_obfs(&validate_o, NULL) &&
           !istlen(validate_o)) {
          /* raw user input that should be printed as 7239 obfs */
          chunk_appendf(out, "_%.*s", (int)smp->data.u.str.data, smp->data.u.str.area);
        }
        /* else: not compliant */
      }
      /* else: cannot be casted to str */
    }
    /* else: smp error */
  }
}

static inline void http_build_7239_header_nodeport(struct buffer *out,
                                                   struct stream *s, struct proxy *curproxy,
                                                   const struct sockaddr_storage *addr,
                                                   struct http_ext_7239_forby *forby)
{
  if (forby->np_mode == HTTP_7239_FORBY_ORIG) {
    if (addr && addr->ss_family == AF_INET)
      chunk_appendf(out, "%d", ntohs(((struct sockaddr_in *)addr)->sin_port));
    else if (addr && addr->ss_family == AF_INET6)
      chunk_appendf(out, "%d", ntohs(((struct sockaddr_in6 *)addr)->sin6_port));
    /* else: not supported */
  }
  else if (forby->np_mode == HTTP_7239_FORBY_SMP && forby->np_expr) {
    struct sample *smp;

    smp = sample_fetch_as_type(curproxy, s->sess, s,
        SMP_OPT_DIR_REQ | SMP_OPT_FINAL, forby->np_expr, SMP_T_STR);
    if (smp) {
      struct ist validate_n = ist2(smp->data.u.str.area, smp->data.u.str.data);
      struct ist validate_o = ist2(smp->data.u.str.area, smp->data.u.str.data);

      /* validate nodeport */
      if (http_7239_extract_nodeport(&validate_n, NULL) &&
          !istlen(validate_n)) {
        /* no special care needed, input is already rfc compliant,
         * just print as regular non quoted string
         */
        chunk_cat(out, &smp->data.u.str);
      }
      else if (http_7239_extract_obfs(&validate_o, NULL) &&
         !istlen(validate_o)) {
        /* raw user input that should be printed as 7239 obfs */
        chunk_appendf(out, "_%.*s", (int)smp->data.u.str.data, smp->data.u.str.area);
      }
      /* else: not compliant */
    }
    /* else: smp error */
  }
}

static inline void http_build_7239_header_node(struct buffer *out,
                                               struct stream *s, struct proxy *curproxy,
                                               const struct sockaddr_storage *addr,
                                               struct http_ext_7239_forby *forby)
{
  size_t offset_start;
  size_t offset_save;

  offset_start = out->data;
  if (forby->np_mode)
    chunk_appendf(out, "\"");
  offset_save = out->data;
  http_build_7239_header_nodename(out, s, curproxy, addr, forby);
  if (offset_save == out->data) {
    /* could not build nodename, either because some
     * data is not available or user is providing bad input
     */
    chunk_appendf(out, "unknown");
  }
  if (forby->np_mode) {
    chunk_appendf(out, ":");
    offset_save = out->data;
    http_build_7239_header_nodeport(out, s, curproxy, addr, forby);
    if (offset_save == out->data) {
      /* could not build nodeport, either because some data is
       * not available or user is providing bad input
       */
      out->data = offset_save - 1;
    }
  }
  if (out->data != offset_start && out->area[offset_start] == '"')
    chunk_appendf(out, "\""); /* add matching end quote */
}

static inline void http_build_7239_header_host(struct buffer *out,
                                               struct stream *s, struct proxy *curproxy,
                                               struct htx *htx, struct http_ext_7239_host *host)
{
  struct http_hdr_ctx ctx = { .blk = NULL };
  char *str = NULL;
  int str_len = 0;

  if (host->mode == HTTP_7239_HOST_ORIG &&
      http_find_header(htx, ist("host"), &ctx, 0)) {
    str = ctx.value.ptr;
    str_len = ctx.value.len;
 print_host:
    {
      struct ist validate = ist2(str, str_len);
      /* host check, to ensure rfc compliant output
       * (assuming host is quoted/escaped)
       */
      if (http_7239_extract_host(&validate, NULL, 1) && !istlen(validate))
        chunk_memcat(out, str, str_len);
      /* else: not compliant or partially compliant */
    }

  }
  else if (host->mode == HTTP_7239_HOST_SMP && host->expr) {
    struct sample *smp;

    smp = sample_fetch_as_type(curproxy, s->sess, s,
        SMP_OPT_DIR_REQ | SMP_OPT_FINAL, host->expr, SMP_T_STR);
    if (smp) {
      str = smp->data.u.str.area;
      str_len = smp->data.u.str.data;
      goto print_host;
    }
    /* else: smp error */
  }
}

/* Tries build 7239 header according to <curproxy> parameters and <s> context
 * It both depends on <curproxy>->http_ext->fwd for config and <s> for request
 * context data.
 * The function will write output to <out> buffer
 * Returns 1 for success and 0 for error (ie: not enough space in buffer)
 */
static int http_build_7239_header(struct buffer *out,
                                  struct stream *s, struct proxy *curproxy, struct htx *htx)
{
  struct connection *cli_conn = objt_conn(strm_sess(s)->origin);

  if (curproxy->http_ext->fwd->p_proto) {
    chunk_appendf(out, "%sproto=%s", ((out->data) ? ";" : ""),
      ((conn_is_ssl(cli_conn)) ? "https" : "http"));
  }
  if (curproxy->http_ext->fwd->p_host.mode) {
    /* always add quotes for host parameter to make output compliance checks simpler */
    chunk_appendf(out, "%shost=\"", ((out->data) ? ";" : ""));
    /* ignore return value for now, but could be useful some day */
    http_build_7239_header_host(out, s, curproxy, htx, &curproxy->http_ext->fwd->p_host);
    chunk_appendf(out, "\"");
  }

  if (curproxy->http_ext->fwd->p_by.nn_mode) {
    const struct sockaddr_storage *dst = sc_dst(s->scf);

    chunk_appendf(out, "%sby=", ((out->data) ? ";" : ""));
    http_build_7239_header_node(out, s, curproxy, dst, &curproxy->http_ext->fwd->p_by);
  }

  if (curproxy->http_ext->fwd->p_for.nn_mode) {
    const struct sockaddr_storage *src = sc_src(s->scf);

    chunk_appendf(out, "%sfor=", ((out->data) ? ";" : ""));
    http_build_7239_header_node(out, s, curproxy, src, &curproxy->http_ext->fwd->p_for);
  }
  if (unlikely(out->data == out->size)) {
    /* not enough space in buffer, error */
    return 0;
  }
  return 1;
}

/* This function will try to inject RFC 7239 forwarded header if
 * configured on the backend (ignored for frontends).
 * Will do nothing if the option is not enabled on the proxy.
 * Returns 1 for success and 0 for failure
 */
int http_handle_7239_header(struct stream *s, struct channel *req)
{
  struct proxy *curproxy = s->be; /* ignore frontend */

  if (curproxy->http_ext && curproxy->http_ext->fwd) {
    struct htx *htx = htxbuf(&req->buf);
    int validate = 1;
    struct http_hdr_ctx find = { .blk = NULL };
    struct http_hdr_ctx last = { .blk = NULL};
    struct ist hdr = ist("forwarded");

    /* ok, let's build forwarded header */
    chunk_reset(&trash);
    if (unlikely(!http_build_7239_header(&trash, s, curproxy, htx)))
      return 0; /* error when building header (bad user conf or memory error) */

    /* validate existing forwarded header (including multiple values),
     * hard stop if error is encountered
     */
    while (http_find_header(htx, hdr, &find, 0)) {
      /* validate current header chunk */
      if (!http_validate_7239_header(find.value, FORWARDED_HEADER_ALL, NULL)) {
        /* at least one error, existing forwarded header not OK, add our own
         * forwarded header, so that it can be trusted
         */
        validate = 0;
        break;
      }
      last = find;
    }
    /* no errors, append our data at the end of existing header */
    if (last.blk && validate) {
      if (unlikely(!http_append_header_value(htx, &last, ist2(trash.area, trash.data))))
        return 0; /* htx error */
    }
    else {
      if (unlikely(!http_add_header(htx, hdr, ist2(trash.area, trash.data))))
        return 0; /* htx error */
    }
  }
  return 1;
}

/*
 * add X-Forwarded-For if either the frontend or the backend
 * asks for it.
 * Returns 1 for success and 0 for failure
 */
int http_handle_xff_header(struct stream *s, struct channel *req)
{
  struct session *sess = s->sess;
  struct http_ext_xff *f_xff = NULL;
  struct http_ext_xff *b_xff = NULL;

  if (sess->fe->http_ext && sess->fe->http_ext->xff) {
    /* frontend */
    f_xff = sess->fe->http_ext->xff;
  }
  if (s->be->http_ext && s->be->http_ext->xff) {
    /* backend */
    b_xff = s->be->http_ext->xff;
  }

  if (f_xff || b_xff) {
    struct htx *htx = htxbuf(&req->buf);
    const struct sockaddr_storage *src = sc_src(s->scf);
    struct http_hdr_ctx ctx = { .blk = NULL };
    struct ist hdr = ((b_xff) ? b_xff->hdr_name : f_xff->hdr_name);

    if ((!f_xff || f_xff->mode == HTTP_XFF_IFNONE) &&
        (!b_xff || b_xff->mode == HTTP_XFF_IFNONE) &&
        http_find_header(htx, hdr, &ctx, 0)) {
      /* The header is set to be added only if none is present
       * and we found it, so don't do anything.
       */
    }
    else if (src && src->ss_family == AF_INET) {
      /* Add an X-Forwarded-For header unless the source IP is
       * in the 'except' network range.
       */
      if ((!f_xff || ipcmp2net(src, &f_xff->except_net)) &&
          (!b_xff || ipcmp2net(src, &b_xff->except_net))) {
        unsigned char *pn = (unsigned char *)&((struct sockaddr_in *)src)->sin_addr;

        /* Note: we rely on the backend to get the header name to be used for
         * x-forwarded-for, because the header is really meant for the backends.
         * However, if the backend did not specify any option, we have to rely
         * on the frontend's header name.
         */
        chunk_printf(&trash, "%d.%d.%d.%d", pn[0], pn[1], pn[2], pn[3]);
        if (unlikely(!http_add_header(htx, hdr, ist2(trash.area, trash.data))))
          return 0;
      }
    }
    else if (src && src->ss_family == AF_INET6) {
      /* Add an X-Forwarded-For header unless the source IP is
       * in the 'except' network range.
       */
      if ((!f_xff || ipcmp2net(src, &f_xff->except_net)) &&
          (!b_xff || ipcmp2net(src, &b_xff->except_net))) {
        char pn[INET6_ADDRSTRLEN];

        inet_ntop(AF_INET6,
            (const void *)&((struct sockaddr_in6 *)(src))->sin6_addr,
            pn, sizeof(pn));

        /* Note: we rely on the backend to get the header name to be used for
         * x-forwarded-for, because the header is really meant for the backends.
         * However, if the backend did not specify any option, we have to rely
         * on the frontend's header name.
         */
        chunk_printf(&trash, "%s", pn);
        if (unlikely(!http_add_header(htx, hdr, ist2(trash.area, trash.data))))
          return 0;
      }
    }
  }
  return 1;
}

/*
 * add X-Original-To if either the frontend or the backend
 * asks for it.
 * Returns 1 for success and 0 for failure
 */
int http_handle_xot_header(struct stream *s, struct channel *req)
{
  struct session *sess = s->sess;
  struct http_ext_xot *f_xot = NULL;
  struct http_ext_xot *b_xot = NULL;

  if (sess->fe->http_ext && sess->fe->http_ext->xot) {
    /* frontend */
    f_xot = sess->fe->http_ext->xot;
  }
  if (s->be->http_ext && s->be->http_ext->xot) {
    /* backend */
    b_xot = s->be->http_ext->xot;
  }

  if (f_xot || b_xot) {
    struct htx *htx = htxbuf(&req->buf);
    const struct sockaddr_storage *dst = sc_dst(s->scf);
    struct ist hdr = ((b_xot) ? b_xot->hdr_name : f_xot->hdr_name);

    if (dst && dst->ss_family == AF_INET) {
      /* Add an X-Original-To header unless the destination IP is
       * in the 'except' network range.
       */
      if ((!f_xot || ipcmp2net(dst, &f_xot->except_net)) &&
          (!b_xot || ipcmp2net(dst, &b_xot->except_net))) {
        unsigned char *pn = (unsigned char *)&((struct sockaddr_in *)dst)->sin_addr;

        /* Note: we rely on the backend to get the header name to be used for
         * x-original-to, because the header is really meant for the backends.
         * However, if the backend did not specify any option, we have to rely
         * on the frontend's header name.
         */
        chunk_printf(&trash, "%d.%d.%d.%d", pn[0], pn[1], pn[2], pn[3]);
        if (unlikely(!http_add_header(htx, hdr, ist2(trash.area, trash.data))))
          return 0;
      }
    }
    else if (dst && dst->ss_family == AF_INET6) {
      /* Add an X-Original-To header unless the source IP is
       * in the 'except' network range.
       */
      if ((!f_xot || ipcmp2net(dst, &f_xot->except_net)) &&
          (!b_xot || ipcmp2net(dst, &b_xot->except_net))) {
        char pn[INET6_ADDRSTRLEN];

        inet_ntop(AF_INET6,
            (const void *)&((struct sockaddr_in6 *)dst)->sin6_addr,
            pn, sizeof(pn));

        /* Note: we rely on the backend to get the header name to be used for
         * x-forwarded-for, because the header is really meant for the backends.
         * However, if the backend did not specify any option, we have to rely
         * on the frontend's header name.
         */
        chunk_printf(&trash, "%s", pn);
        if (unlikely(!http_add_header(htx, hdr, ist2(trash.area, trash.data))))
          return 0;
      }
    }
  }
  return 1;
}

/*
 * =========== CONFIG ===========
 * below are helpers to parse http ext options from the config
 */
static int proxy_http_parse_oom(const char *file, int linenum)
{
  int err_code = 0;

  ha_alert("parsing [%s:%d]: out of memory.\n", file, linenum);
  err_code |= ERR_ALERT | ERR_ABORT;
  return err_code;
}

static inline int _proxy_http_parse_7239_expr(char **args, int *cur_arg,
                                              const char *file, int linenum,
                                              char **expr_s)
{
  int err_code = 0;

  if (!*args[*cur_arg + 1]) {
    ha_alert("parsing [%s:%d]: '%s' expects <expr> as argument.\n",
       file, linenum, args[*cur_arg]);
    err_code |= ERR_ALERT | ERR_FATAL;
    goto out;
  }
  *cur_arg += 1;
  ha_free(expr_s);
  *expr_s = strdup(args[*cur_arg]);
  if (!*expr_s)
    return proxy_http_parse_oom(file, linenum);
  *cur_arg += 1;
 out:
  return err_code;
}

/* forwarded/7239 RFC: tries to parse "option forwarded" config keyword
 * Returns a composition of ERR_ABORT, ERR_ALERT, ERR_FATAL, ERR_WARN
 */
int proxy_http_parse_7239(char **args, int cur_arg,
                          struct proxy *curproxy, const struct proxy *defpx,
                          const char *file, int linenum)
{
  struct http_ext_7239 *fwd;
  int err_code = 0;

  if (warnifnotcap(curproxy, PR_CAP_BE, file, linenum, "option forwarded", NULL)) {
    /* option is ignored for frontends */
    err_code |= ERR_WARN;
    goto out;
  }

  if (!http_ext_7239_prepare(curproxy))
    return proxy_http_parse_oom(file, linenum);

  fwd = curproxy->http_ext->fwd;

  fwd->p_proto = 0;
  fwd->p_host.mode = 0;
  fwd->p_for.nn_mode = 0;
  fwd->p_for.np_mode = 0;
  fwd->p_by.nn_mode = 0;
  fwd->p_by.np_mode = 0;
  ha_free(&fwd->c_file);
  fwd->c_file = strdup(file);
  fwd->c_line = linenum;

  /* start at 2, since 0+1 = "option" "forwarded" */
  cur_arg = 2;
  if (!*(args[cur_arg])) {
    /* no optional argument provided, use default settings */
    fwd->p_for.nn_mode = HTTP_7239_FORBY_ORIG; /* enable for and mimic xff */
    fwd->p_proto = 1; /* enable proto */
    goto out;
  }
  /* loop to go through optional arguments */
  while (*(args[cur_arg])) {
    if (strcmp(args[cur_arg], "proto") == 0) {
      fwd->p_proto = 1;
      cur_arg += 1;
    } else if (strcmp(args[cur_arg], "host") == 0) {
      fwd->p_host.mode = HTTP_7239_HOST_ORIG;
      cur_arg += 1;
    } else if (strcmp(args[cur_arg], "host-expr") == 0) {
      fwd->p_host.mode = HTTP_7239_HOST_SMP;
      err_code |= _proxy_http_parse_7239_expr(args, &cur_arg, file, linenum,
                &fwd->p_host.expr_s);
      if (err_code & ERR_CODE)
        goto out;
    } else if (strcmp(args[cur_arg], "by") == 0) {
      fwd->p_by.nn_mode = HTTP_7239_FORBY_ORIG;
      cur_arg += 1;
    } else if (strcmp(args[cur_arg], "by-expr") == 0) {
      fwd->p_by.nn_mode = HTTP_7239_FORBY_SMP;
      err_code |= _proxy_http_parse_7239_expr(args, &cur_arg, file, linenum,
                &fwd->p_by.nn_expr_s);
      if (err_code & ERR_CODE)
        goto out;
    } else if (strcmp(args[cur_arg], "for") == 0) {
      fwd->p_for.nn_mode = HTTP_7239_FORBY_ORIG;
      cur_arg += 1;
    } else if (strcmp(args[cur_arg], "for-expr") == 0) {
      fwd->p_for.nn_mode = HTTP_7239_FORBY_SMP;
      err_code |= _proxy_http_parse_7239_expr(args, &cur_arg, file, linenum,
                &fwd->p_for.nn_expr_s);
      if (err_code & ERR_CODE)
        goto out;
    } else if (strcmp(args[cur_arg], "by_port") == 0) {
      fwd->p_by.np_mode = HTTP_7239_FORBY_ORIG;
      cur_arg += 1;
    } else if (strcmp(args[cur_arg], "by_port-expr") == 0) {
      fwd->p_by.np_mode = HTTP_7239_FORBY_SMP;
      err_code |= _proxy_http_parse_7239_expr(args, &cur_arg, file, linenum,
                &fwd->p_by.np_expr_s);
      if (err_code & ERR_CODE)
        goto out;
    } else if (strcmp(args[cur_arg], "for_port") == 0) {
      fwd->p_for.np_mode = HTTP_7239_FORBY_ORIG;
      cur_arg += 1;
    } else if (strcmp(args[cur_arg], "for_port-expr") == 0) {
      fwd->p_for.np_mode = HTTP_7239_FORBY_SMP;
      err_code |= _proxy_http_parse_7239_expr(args, &cur_arg, file, linenum,
                &fwd->p_for.np_expr_s);
      if (err_code & ERR_CODE)
        goto out;
    } else {
      /* unknown suboption - catchall */
      ha_alert("parsing [%s:%d] : '%s %s' only supports optional values: 'proto', 'host', "
         "'host-expr', 'by', 'by-expr', 'by_port', 'by_port-expr', "
         "'for', 'for-expr', 'for_port' and 'for_port-expr'.\n",
         file, linenum, args[0], args[1]);
      err_code |= ERR_ALERT | ERR_FATAL;
      goto out;
    }
  } /* end while loop */

  /* consistency check */
  if (fwd->p_by.np_mode &&
      !fwd->p_by.nn_mode) {
    fwd->p_by.np_mode = 0;
    ha_free(&fwd->p_by.np_expr_s);
    ha_warning("parsing [%s:%d] : '%s %s' : '%s' will be ignored because both 'by' "
         "and 'by-expr' are unset\n",
         file, linenum, args[0], args[1],
         ((fwd->p_by.np_mode == HTTP_7239_FORBY_ORIG) ? "by_port" : "by_port-expr"));
    err_code |= ERR_WARN;
  }
  if (fwd->p_for.np_mode &&
      !fwd->p_for.nn_mode) {
    fwd->p_for.np_mode = 0;
    ha_free(&fwd->p_for.np_expr_s);
    ha_warning("parsing [%s:%d] : '%s %s' : '%s' will be ignored because both 'for' "
         "and 'for-expr' are unset\n",
         file, linenum, args[0], args[1],
         ((fwd->p_for.np_mode == HTTP_7239_FORBY_ORIG) ? "for_port" : "for_port-expr"));
    err_code |= ERR_WARN;
  }

 out:
  return err_code;
}

/* rfc7239 forwarded option needs a postparsing step
 * to convert parsing hints into runtime usable sample expressions
 * Returns a composition of ERR_NONE, ERR_FATAL, ERR_ALERT, ERR_WARN
 */
int proxy_http_compile_7239(struct proxy *curproxy)
{
  struct http_ext_7239 *fwd;
  int err = ERR_NONE;
  int loop;

  if (!(curproxy->cap & PR_CAP_BE)) {
    /* no backend cap: not supported (ie: frontend) */
    goto out;
  }

  /* should not happen (test should be performed after BE cap test) */
  BUG_ON(!curproxy->http_ext || !curproxy->http_ext->fwd);

  curproxy->conf.args.ctx = ARGC_OPT; /* option */
  curproxy->conf.args.file = curproxy->http_ext->fwd->c_file;
  curproxy->conf.args.line = curproxy->http_ext->fwd->c_line;
  fwd = curproxy->http_ext->fwd;

  /* it is important that we keep iterating on error to make sure
   * all fwd config fields are in the same state (post-parsing state)
   */
  for (loop = 0; loop < 5; loop++) {
    char **expr_str = NULL;
    struct sample_expr **expr = NULL;
    struct sample_expr *cur_expr;
    char *err_str = NULL;
    int smp = 0;
    int idx = 0;

    switch (loop) {
      case 0:
        /* host */
        expr_str = &fwd->p_host.expr_s;
        expr = &fwd->p_host.expr;
        smp = (fwd->p_host.mode == HTTP_7239_HOST_SMP);
        break;
      case 1:
        /* by->node */
        expr_str = &fwd->p_by.nn_expr_s;
        expr = &fwd->p_by.nn_expr;
        smp = (fwd->p_by.nn_mode == HTTP_7239_FORBY_SMP);
        break;
      case 2:
        /* by->nodeport */
        expr_str = &fwd->p_by.np_expr_s;
        expr = &fwd->p_by.np_expr;
        smp = (fwd->p_by.np_mode == HTTP_7239_FORBY_SMP);
        break;
      case 3:
        /* for->node */
        expr_str = &fwd->p_for.nn_expr_s;
        expr = &fwd->p_for.nn_expr;
        smp = (fwd->p_for.nn_mode == HTTP_7239_FORBY_SMP);
        break;
      case 4:
        /* for->nodeport */
        expr_str = &fwd->p_for.np_expr_s;
        expr = &fwd->p_for.np_expr;
        smp = (fwd->p_for.np_mode == HTTP_7239_FORBY_SMP);
        break;
    }
    if (!smp)
      continue; /* no expr */

    /* expr and expr_str cannot be NULL past this point */
    BUG_ON(!expr || !expr_str);

    if (!*expr_str) {
      /* should not happen unless system memory exhaustion */
      ha_alert("%s '%s' [%s:%d]: failed to parse 'option forwarded' expression : %s.\n",
         proxy_type_str(curproxy), curproxy->id,
         fwd->c_file, fwd->c_line,
         "memory error");
      err |= ERR_ALERT | ERR_FATAL;
      continue;
    }

    cur_expr =
      sample_parse_expr((char*[]){*expr_str, NULL}, &idx,
            fwd->c_file,
            fwd->c_line,
            &err_str, &curproxy->conf.args, NULL);

    if (!cur_expr) {
      ha_alert("%s '%s' [%s:%d]: failed to parse 'option forwarded' expression '%s' in : %s.\n",
         proxy_type_str(curproxy), curproxy->id,
         fwd->c_file, fwd->c_line,
         *expr_str, err_str);
      ha_free(&err_str);
      err |= ERR_ALERT | ERR_FATAL;
    }
    else if (!(cur_expr->fetch->val & SMP_VAL_BE_HRQ_HDR)) {
      /* fetch not available in this context: sample expr is resolved
       * within backend right after headers are processed.
       * (in http_process_request())
       * -> we simply warn the user about the misuse
       */
      ha_warning("%s '%s' [%s:%d]: in 'option forwarded' sample expression '%s' : "
           "some args extract information from '%s', "
           "none of which is available here.\n",
           proxy_type_str(curproxy), curproxy->id,
           fwd->c_file, fwd->c_line,
           *expr_str, sample_ckp_names(cur_expr->fetch->use));
      err |= ERR_WARN;
    }
    /* post parsing individual expr cleanup */
    ha_free(expr_str);

    /* expr assignment */
    *expr = cur_expr;
  }
  curproxy->conf.args.file = NULL;
  curproxy->conf.args.line = 0;

  /* post parsing general cleanup */
  ha_free(&fwd->c_file);
  fwd->c_line = 0;

  fwd->c_mode = 1; /* parsing completed */

 out:
  return err;
}

/* x-forwarded-for: tries to parse "option forwardfor" config keyword
 * Returns a composition of ERR_NONE, ERR_FATAL, ERR_ALERT
 */
int proxy_http_parse_xff(char **args, int cur_arg,
                         struct proxy *curproxy, const struct proxy *defpx,
                         const char *file, int linenum)
{
  struct http_ext_xff *xff;
  int err_code = 0;

  if (!http_ext_xff_prepare(curproxy))
    return proxy_http_parse_oom(file, linenum);

  xff = curproxy->http_ext->xff;

  /* insert x-forwarded-for field, but not for the IP address listed as an except.
   * set default options (ie: bitfield, header name, etc)
   */

  xff->mode = HTTP_XFF_ALWAYS;

  istfree(&xff->hdr_name);
  xff->hdr_name = istdup(ist(DEF_XFORWARDFOR_HDR));
  if (!isttest(xff->hdr_name))
    return proxy_http_parse_oom(file, linenum);
  xff->except_net.family = AF_UNSPEC;

  /* loop to go through arguments - start at 2, since 0+1 = "option" "forwardfor" */
  cur_arg = 2;
  while (*(args[cur_arg])) {
    if (strcmp(args[cur_arg], "except") == 0) {
      unsigned char mask;
      int i;

      /* suboption except - needs additional argument for it */
      if (*(args[cur_arg+1]) &&
          str2net(args[cur_arg+1], 1, &xff->except_net.addr.v4.ip, &xff->except_net.addr.v4.mask)) {
        xff->except_net.family = AF_INET;
        xff->except_net.addr.v4.ip.s_addr &= xff->except_net.addr.v4.mask.s_addr;
      }
      else if (*(args[cur_arg+1]) &&
         str62net(args[cur_arg+1], &xff->except_net.addr.v6.ip, &mask)) {
        xff->except_net.family = AF_INET6;
        len2mask6(mask, &xff->except_net.addr.v6.mask);
        for (i = 0; i < 16; i++)
          xff->except_net.addr.v6.ip.s6_addr[i] &= xff->except_net.addr.v6.mask.s6_addr[i];
      }
      else {
        ha_alert("parsing [%s:%d] : '%s %s %s' expects <address>[/mask] as argument.\n",
           file, linenum, args[0], args[1], args[cur_arg]);
        err_code |= ERR_ALERT | ERR_FATAL;
        goto out;
      }
      /* flush useless bits */
      cur_arg += 2;
    } else if (strcmp(args[cur_arg], "header") == 0) {
      /* suboption header - needs additional argument for it */
      if (*(args[cur_arg+1]) == 0) {
        ha_alert("parsing [%s:%d] : '%s %s %s' expects <header_name> as argument.\n",
           file, linenum, args[0], args[1], args[cur_arg]);
        err_code |= ERR_ALERT | ERR_FATAL;
        goto out;
      }
      istfree(&xff->hdr_name);
      xff->hdr_name = istdup(ist(args[cur_arg+1]));
      if (!isttest(xff->hdr_name))
        return proxy_http_parse_oom(file, linenum);
      cur_arg += 2;
    } else if (strcmp(args[cur_arg], "if-none") == 0) {
      xff->mode = HTTP_XFF_IFNONE;
      cur_arg += 1;
    } else {
      /* unknown suboption - catchall */
      ha_alert("parsing [%s:%d] : '%s %s' only supports optional values: 'except', 'header' and 'if-none'.\n",
         file, linenum, args[0], args[1]);
      err_code |= ERR_ALERT | ERR_FATAL;
      goto out;
    }
  } /* end while loop */
 out:
  return err_code;
}

/* x-original-to: tries to parse "option originalto" config keyword
 * Returns a composition of ERR_NONE, ERR_FATAL, ERR_ALERT
 */
int proxy_http_parse_xot(char **args, int cur_arg,
                         struct proxy *curproxy, const struct proxy *defpx,
                         const char *file, int linenum)
{
  struct http_ext_xot *xot;
  int err_code = 0;

  if (!http_ext_xot_prepare(curproxy))
    return proxy_http_parse_oom(file, linenum);

  xot = curproxy->http_ext->xot;

  /* insert x-original-to field, but not for the IP address listed as an except.
   * set default options (ie: bitfield, header name, etc)
   */

  istfree(&xot->hdr_name);
  xot->hdr_name = istdup(ist(DEF_XORIGINALTO_HDR));
  if (!isttest(xot->hdr_name))
    return proxy_http_parse_oom(file, linenum);
  xot->except_net.family = AF_UNSPEC;

  /* loop to go through arguments - start at 2, since 0+1 = "option" "originalto" */
  cur_arg = 2;
  while (*(args[cur_arg])) {
    if (strcmp(args[cur_arg], "except") == 0) {
      unsigned char mask;
      int i;

      /* suboption except - needs additional argument for it */
      if (*(args[cur_arg+1]) &&
          str2net(args[cur_arg+1], 1, &xot->except_net.addr.v4.ip, &xot->except_net.addr.v4.mask)) {
        xot->except_net.family = AF_INET;
        xot->except_net.addr.v4.ip.s_addr &= xot->except_net.addr.v4.mask.s_addr;
      }
      else if (*(args[cur_arg+1]) &&
         str62net(args[cur_arg+1], &xot->except_net.addr.v6.ip, &mask)) {
        xot->except_net.family = AF_INET6;
        len2mask6(mask, &xot->except_net.addr.v6.mask);
        for (i = 0; i < 16; i++)
          xot->except_net.addr.v6.ip.s6_addr[i] &= xot->except_net.addr.v6.mask.s6_addr[i];
      }
      else {
        ha_alert("parsing [%s:%d] : '%s %s %s' expects <address>[/mask] as argument.\n",
           file, linenum, args[0], args[1], args[cur_arg]);
        err_code |= ERR_ALERT | ERR_FATAL;
        goto out;
      }
      cur_arg += 2;
    } else if (strcmp(args[cur_arg], "header") == 0) {
      /* suboption header - needs additional argument for it */
      if (*(args[cur_arg+1]) == 0) {
        ha_alert("parsing [%s:%d] : '%s %s %s' expects <header_name> as argument.\n",
           file, linenum, args[0], args[1], args[cur_arg]);
        err_code |= ERR_ALERT | ERR_FATAL;
        goto out;
      }
      istfree(&xot->hdr_name);
      xot->hdr_name = istdup(ist(args[cur_arg+1]));
      if (!isttest(xot->hdr_name))
        return proxy_http_parse_oom(file, linenum);
      cur_arg += 2;
    } else {
      /* unknown suboption - catchall */
      ha_alert("parsing [%s:%d] : '%s %s' only supports optional values: 'except' and 'header'.\n",
         file, linenum, args[0], args[1]);
      err_code |= ERR_ALERT | ERR_FATAL;
      goto out;
    }
  } /* end while loop */

 out:
  return err_code;
}

/*
 * =========== MGMT ===========
 * below are helpers to manage http ext options
 */

/* Ensure http_ext->fwd is properly allocated and
 * initialized for <curproxy>.
 * The function will leverage http_ext_prepare() to make
 * sure http_ext is properly allocated and initialized as well.
 * Returns 1 for success and 0 for failure (memory error)
 */
int http_ext_7239_prepare(struct proxy *curproxy)
{
  struct http_ext_7239 *fwd;

  if (!http_ext_prepare(curproxy))
    return 0;
  if (curproxy->http_ext->fwd)
    return 1; /* nothing to do */

  fwd = malloc(sizeof(*fwd));
  if (!fwd)
    return 0;
  /* initialize fwd mandatory fields */
  fwd->c_mode = 0; /* pre-compile (parse) time */
  fwd->c_file = NULL;
  fwd->p_host.expr_s = NULL;
  fwd->p_by.nn_expr_s = NULL;
  fwd->p_by.np_expr_s = NULL;
  fwd->p_for.nn_expr_s = NULL;
  fwd->p_for.np_expr_s = NULL;
  /* assign */
  curproxy->http_ext->fwd = fwd;
  return 1;
}

/* Ensure http_ext->xff is properly allocated and
 * initialized for <curproxy>.
 * The function will leverage http_ext_prepare() to make
 * sure http_ext is properly allocated and initialized as well.
 * Returns 1 for success and 0 for failure (memory error)
 */
int http_ext_xff_prepare(struct proxy *curproxy)
{
  struct http_ext_xff *xff;

  if (!http_ext_prepare(curproxy))
    return 0;
  if (curproxy->http_ext->xff)
    return 1; /* nothing to do */

  xff = malloc(sizeof(*xff));
  if (!xff)
    return 0;
  /* initialize xff mandatory fields */
  xff->hdr_name = IST_NULL;
  /* assign */
  curproxy->http_ext->xff = xff;
  return 1;
}

/* Ensure http_ext->xot is properly allocated and
 * initialized for <curproxy>.
 * The function will leverage http_ext_prepare() to make
 * sure http_ext is properly allocated and initialized as well.
 * Returns 1 for success and 0 for failure (memory error)
 */
int http_ext_xot_prepare(struct proxy *curproxy)
{
  struct http_ext_xot *xot;

  if (!http_ext_prepare(curproxy))
    return 0;
  if (curproxy->http_ext->xot)
    return 1; /* nothing to do */

  xot = malloc(sizeof(*xot));
  if (!xot)
    return 0;
  /* initialize xot mandatory fields */
  xot->hdr_name = IST_NULL;
  /* assign */
  curproxy->http_ext->xot = xot;
  return 1;
}

/* deep clean http_ext->fwd parameter for <curproxy>
 * http_ext->fwd will be freed
 * clean behavior will differ depending on http_ext->fwd
 * state. If fwd is in 'parsed' state, parsing hints will be
 * cleaned. Else, it means fwd is in 'compiled' state, in this
 * case we're cleaning compiled results.
 * This is because parse and compile memory areas are shared in
 * a single union to optimize struct http_ext_7239 size.
 */
void http_ext_7239_clean(struct proxy *curproxy)
{
  struct http_ext_7239 *clean;

  if (!curproxy->http_ext)
    return;
  clean = curproxy->http_ext->fwd;
  if (!clean)
    return; /* nothing to do */
  if (!clean->c_mode) {
    /* parsed */
    ha_free(&clean->c_file);
    ha_free(&clean->p_host.expr_s);
    ha_free(&clean->p_by.nn_expr_s);
    ha_free(&clean->p_by.np_expr_s);
    ha_free(&clean->p_for.nn_expr_s);
    ha_free(&clean->p_for.np_expr_s);
  }
  else {
    /* compiled */
    release_sample_expr(clean->p_host.expr);
    clean->p_host.expr = NULL;
    release_sample_expr(clean->p_by.nn_expr);
    clean->p_by.nn_expr = NULL;
    release_sample_expr(clean->p_by.np_expr);
    clean->p_by.np_expr = NULL;
    release_sample_expr(clean->p_for.nn_expr);
    clean->p_for.nn_expr = NULL;
    release_sample_expr(clean->p_for.np_expr);
    clean->p_for.np_expr = NULL;
  }
  /* free fwd */
  ha_free(&curproxy->http_ext->fwd);
}

/* deep clean http_ext->xff parameter for <curproxy>
 * http_ext->xff will be freed
 */
void http_ext_xff_clean(struct proxy *curproxy)
{
  struct http_ext_xff *clean;

  if (!curproxy->http_ext)
    return;
  clean = curproxy->http_ext->xff;
  if (!clean)
    return; /* nothing to do */
  istfree(&clean->hdr_name);
  /* free xff */
  ha_free(&curproxy->http_ext->xff);
}

/* deep clean http_ext->xot parameter for <curproxy>
 * http_ext->xot will be freed
 */
void http_ext_xot_clean(struct proxy *curproxy)
{
  struct http_ext_xot *clean;

  if (!curproxy->http_ext)
    return;
  clean = curproxy->http_ext->xot;
  if (!clean)
    return; /* nothing to do */
  istfree(&clean->hdr_name);
  /* free xot */
  ha_free(&curproxy->http_ext->xot);
}

/* duplicate http_ext->fwd parameters from <def> to <cpy>
 * performs the required memory allocation and initialization
 */
void http_ext_7239_dup(const struct proxy *def, struct proxy *cpy)
{
  struct http_ext_7239 *dest = NULL;
  struct http_ext_7239 *orig = NULL;

  /* feature requires backend cap */
  if (!(cpy->cap & PR_CAP_BE))
    return;

  if (def->http_ext == NULL || def->http_ext->fwd == NULL)
    return;

  orig = def->http_ext->fwd;

  if (orig->c_mode)
    return; /* copy not supported once compiled */

  if (!http_ext_7239_prepare(cpy))
    return;

  dest = cpy->http_ext->fwd;

  if (orig->c_file)
    dest->c_file = strdup(orig->c_file);
  dest->c_line = orig->c_line;
  /* proto */
  dest->p_proto = orig->p_proto;
  /* host */
  dest->p_host.mode = orig->p_host.mode;
  if (orig->p_host.expr_s)
    dest->p_host.expr_s = strdup(orig->p_host.expr_s);
  /* by - nodename */
  dest->p_by.nn_mode = orig->p_by.nn_mode;
  if (orig->p_by.nn_expr_s)
    dest->p_by.nn_expr_s = strdup(orig->p_by.nn_expr_s);
  /* by - nodeport */
  dest->p_by.np_mode = orig->p_by.np_mode;
  if (orig->p_by.np_expr_s)
    dest->p_by.np_expr_s = strdup(orig->p_by.np_expr_s);
  /* for - nodename */
  dest->p_for.nn_mode = orig->p_for.nn_mode;
  if (orig->p_for.nn_expr_s)
    dest->p_for.nn_expr_s = strdup(orig->p_for.nn_expr_s);
  /* for - nodeport */
  dest->p_for.np_mode = orig->p_for.np_mode;
  if (orig->p_for.np_expr_s)
    dest->p_for.np_expr_s = strdup(orig->p_for.np_expr_s);
}

/* duplicate http_ext->xff parameters from <def> to <cpy>
 * performs the required memory allocation and initialization
 */
void http_ext_xff_dup(const struct proxy *def, struct proxy *cpy)
{
  struct http_ext_xff *dest = NULL;
  struct http_ext_xff *orig = NULL;

  if (def->http_ext == NULL || def->http_ext->xff == NULL ||
      !http_ext_xff_prepare(cpy))
    return;

  orig = def->http_ext->xff;
  dest = cpy->http_ext->xff;

  if (isttest(orig->hdr_name))
    dest->hdr_name = istdup(orig->hdr_name);
  dest->mode = orig->mode;
  dest->except_net = orig->except_net;
}

/* duplicate http_ext->xot parameters from <def> to <cpy>
 * performs the required memory allocation and initialization
 */
void http_ext_xot_dup(const struct proxy *def, struct proxy *cpy)
{
  struct http_ext_xot *dest = NULL;
  struct http_ext_xot *orig = NULL;

  if (def->http_ext == NULL || def->http_ext->xot == NULL ||
      !http_ext_xot_prepare(cpy))
    return;

  orig = def->http_ext->xot;
  dest = cpy->http_ext->xot;

  if (isttest(orig->hdr_name))
    dest->hdr_name = istdup(orig->hdr_name);
  dest->except_net = orig->except_net;
}

/* Allocate new http_ext and initialize it
 * if needed
 * Returns 1 for success and 0 for failure
 */
int http_ext_prepare(struct proxy *curproxy)
{
  if (curproxy->http_ext)
    return 1; /* nothing to do */

  curproxy->http_ext = malloc(sizeof(*curproxy->http_ext));
  if (!curproxy->http_ext)
    return 0; /* failure */
  /* first init, set supported ext to NULL */
  curproxy->http_ext->fwd = NULL;
  curproxy->http_ext->xff = NULL;
  curproxy->http_ext->xot = NULL;
  return 1;
}

/* duplicate existing http_ext from <defproxy> to <curproxy>
 */
void http_ext_dup(const struct proxy *defproxy, struct proxy *curproxy)
{
  /* copy defproxy.http_ext members */
  http_ext_7239_dup(defproxy, curproxy);
  http_ext_xff_dup(defproxy, curproxy);
  http_ext_xot_dup(defproxy, curproxy);
}

/* deep clean http_ext for <curproxy> (if previously allocated)
 */
void http_ext_clean(struct proxy *curproxy)
{
  if (!curproxy->http_ext)
    return; /* nothing to do */
  /* first, free supported ext */
  http_ext_7239_clean(curproxy);
  http_ext_xff_clean(curproxy);
  http_ext_xot_clean(curproxy);

  /* then, free http_ext */
  ha_free(&curproxy->http_ext);
}

/* soft clean (only clean http_ext if no more options are used) */
void http_ext_softclean(struct proxy *curproxy)
{
  if (!curproxy->http_ext)
    return; /* nothing to do */
  if (!curproxy->http_ext->fwd &&
      !curproxy->http_ext->xff &&
      !curproxy->http_ext->xot) {
    /* no more use for http_ext, all options are disabled */
    http_ext_clean(curproxy);
  }
}

/* Perform some consistency checks on px.http_ext after parsing
 * is completed.
 * We make sure to perform a softclean in case some options were
 * to be disabled in this check. This way we can release some memory.
 * Returns a composition of ERR_NONE, ERR_ALERT, ERR_FATAL, ERR_WARN
 */
static int check_http_ext_postconf(struct proxy *px) {
  int err = ERR_NONE;

  if (px->http_ext) {
    /* consistency check for http_ext */
    if (px->mode != PR_MODE_HTTP && !(px->options & PR_O_HTTP_UPG)) {
      /* http is disabled on px, yet it is required by http_ext */
      if (px->http_ext->fwd) {
        ha_warning("'option %s' ignored for %s '%s' as it requires HTTP mode.\n",
             "forwarded", proxy_type_str(px), px->id);
        err |= ERR_WARN;
        http_ext_7239_clean(px);
      }
      if (px->http_ext->xff) {
        ha_warning("'option %s' ignored for %s '%s' as it requires HTTP mode.\n",
             "forwardfor", proxy_type_str(px), px->id);
        err |= ERR_WARN;
        http_ext_xff_clean(px);
      }
      if (px->http_ext->xot) {
        ha_warning("'option %s' ignored for %s '%s' as it requires HTTP mode.\n",
             "originalto", proxy_type_str(px), px->id);
        err |= ERR_WARN;
        http_ext_xot_clean(px);
      }
    } else if (px->http_ext->fwd) {
      /* option "forwarded" may need to compile its expressions */
      err |= proxy_http_compile_7239(px);
    }
    /* http_ext post init early cleanup */
    http_ext_softclean(px);

  }
  return err;
}

REGISTER_POST_PROXY_CHECK(check_http_ext_postconf);
/*
 * =========== CONV ===========
 * related converters
 */

/* input: string representing 7239 forwarded header single value
 * does not take arguments
 * output: 1 if header is RFC compliant, 0 otherwise
 */
static int sample_conv_7239_valid(const struct arg *args, struct sample *smp, void *private)
{
  struct ist input = ist2(smp->data.u.str.area, smp->data.u.str.data);

  smp->data.type = SMP_T_BOOL;
  smp->data.u.sint = !!http_validate_7239_header(input, FORWARDED_HEADER_ALL, NULL);
  return 1;
}

/* input: string representing 7239 forwarded header single value
 * argument: parameter name to look for in the header
 * output: header parameter raw value, as a string
 */
static int sample_conv_7239_field(const struct arg *args, struct sample *smp, void *private)
{
  struct ist input = ist2(smp->data.u.str.area, smp->data.u.str.data);
  struct buffer *output;
  struct forwarded_header_ctx ctx;
  int validate;
  int field = 0;

  if (strcmp(args->data.str.area, "proto") == 0)
    field = FORWARDED_HEADER_PROTO;
  else if (strcmp(args->data.str.area, "host") == 0)
    field = FORWARDED_HEADER_HOST;
  else if (strcmp(args->data.str.area, "for") == 0)
    field = FORWARDED_HEADER_FOR;
  else if (strcmp(args->data.str.area, "by") == 0)
    field = FORWARDED_HEADER_BY;

  validate = http_validate_7239_header(input, FORWARDED_HEADER_ALL, &ctx);
  if (!(validate & field))
    return 0; /* invalid header or header does not contain field */
  output = get_trash_chunk();
  switch (field) {
    case FORWARDED_HEADER_PROTO:
      if (ctx.proto == FORWARDED_HEADER_HTTP)
        chunk_appendf(output, "http");
      else if (ctx.proto == FORWARDED_HEADER_HTTPS)
        chunk_appendf(output, "https");
      break;
    case FORWARDED_HEADER_HOST:
      chunk_istcat(output, ctx.host);
      break;
    case FORWARDED_HEADER_FOR:
      chunk_istcat(output, ctx.nfor.raw);
      break;
    case FORWARDED_HEADER_BY:
      chunk_istcat(output, ctx.nby.raw);
      break;
    default:
      break;
  }
  smp->flags &= ~SMP_F_CONST;
  smp->data.type = SMP_T_STR;
  smp->data.u.str = *output;
  return 1;
}

/* input: substring representing 7239 forwarded header node
 * output: forwarded header nodename translated to either
 * ipv4 address, ipv6 address or str
 * ('_' prefix if obfuscated, or "unknown" if unknown)
 */
static int sample_conv_7239_n2nn(const struct arg *args, struct sample *smp, void *private)
{
  struct ist input = ist2(smp->data.u.str.area, smp->data.u.str.data);
  struct forwarded_header_node ctx;
  struct buffer *output;

  if (http_7239_extract_node(&input, &ctx, 1) == 0)
    return 0; /* could not extract node */
  switch (ctx.nodename.type) {
    case FORWARDED_HEADER_UNK:
      output = get_trash_chunk();
      chunk_appendf(output, "unknown");
      smp->flags &= ~SMP_F_CONST;
      smp->data.type = SMP_T_STR;
      smp->data.u.str = *output;
      break;
    case FORWARDED_HEADER_OBFS:
      output = get_trash_chunk();
      chunk_appendf(output, "_"); /* append obfs prefix */
      chunk_istcat(output, ctx.nodename.obfs);
      smp->flags &= ~SMP_F_CONST;
      smp->data.type = SMP_T_STR;
      smp->data.u.str = *output;
      break;
    case FORWARDED_HEADER_IP:
      if (ctx.nodename.ip.ss_family == AF_INET) {
        smp->data.type = SMP_T_IPV4;
        smp->data.u.ipv4 = ((struct sockaddr_in *)&ctx.nodename.ip)->sin_addr;
      }
      else if (ctx.nodename.ip.ss_family == AF_INET6) {
        smp->data.type = SMP_T_IPV6;
        smp->data.u.ipv6 = ((struct sockaddr_in6 *)&ctx.nodename.ip)->sin6_addr;
      }
      else
        return 0; /* unsupported */
      break;
    default:
      return 0; /* unsupported */
  }
  return 1;
}

/* input: substring representing 7239 forwarded header node
 * output: forwarded header nodeport translated to either
 * integer or str for obfuscated ('_' prefix)
 */
static int sample_conv_7239_n2np(const struct arg *args, struct sample *smp, void *private)
{
  struct ist input = ist2(smp->data.u.str.area, smp->data.u.str.data);
  struct forwarded_header_node ctx;
  struct buffer *output;

  if (http_7239_extract_node(&input, &ctx, 1) == 0)
    return 0; /* could not extract node */

  switch (ctx.nodeport.type) {
    case FORWARDED_HEADER_UNK:
      return 0; /* not provided */
    case FORWARDED_HEADER_OBFS:
      output = get_trash_chunk();
      chunk_appendf(output, "_"); /* append obfs prefix */
      chunk_istcat(output, ctx.nodeport.obfs);
      smp->flags &= ~SMP_F_CONST;
      smp->data.type = SMP_T_STR;
      smp->data.u.str = *output;
      break;
    case FORWARDED_HEADER_PORT:
      smp->data.type = SMP_T_SINT;
      smp->data.u.sint = ctx.nodeport.port;
      break;
    default:
      return 0; /* unsupported */
  }

  return 1;
}

/*
 * input: ipv4 address, ipv6 address or str (empty string will result in
 * "unknown" identifier, else string will be translated to _obfs
 * identifier, prefixed by '_'. Must comply with RFC7239 charset)
 *
 * output: rfc7239-compliant forwarded header nodename
 */
static int sample_conv_7239_nn(const struct arg *args, struct sample *smp, void *private)
{
  struct buffer *trash = get_trash_chunk();

  switch (smp->data.type) {
    case SMP_T_IPV4:
    {
      unsigned char *pn = (unsigned char *)&(smp->data.u.ipv4);

      chunk_printf(trash, "%d.%d.%d.%d", pn[0], pn[1], pn[2], pn[3]);
      break;
    }
    case SMP_T_IPV6:
      _7239_print_ip6(trash, &smp->data.u.ipv6, 1);
      break;
    case SMP_T_STR:
 case_str:
    {
      struct ist validate_n = ist2(smp->data.u.str.area, smp->data.u.str.data);

      if (!istlen(validate_n)) {
        // empty -> unknown
        chunk_printf(trash, "unknown");
        break;
      }

      if (!(http_7239_extract_obfs(&validate_n, NULL) && !istlen(validate_n)))
        return 0; /* invalid input */
      // output with '_' prefix
      chunk_printf(trash, "_%.*s", (int)smp->data.u.str.data, smp->data.u.str.area);
      break;
    }
    default:
    {
      if (sample_casts[smp->data.type][SMP_T_STR] &&
                            sample_casts[smp->data.type][SMP_T_STR](smp))
        goto case_str;
      return 0; /* unexpected */
    }

  }

  smp->data.u.str = *trash;
  smp->data.type = SMP_T_STR;
  smp->flags &= ~SMP_F_CONST;

  return 1;
}

/*
 * input: unsigned integer or str (string will be translated to _obfs
 * identifier, prefixed by '_'. Must comply with RFC7239 charset)
 *
 * output: rfc7239-compliant forwarded header nodeport
 */
static int sample_conv_7239_np(const struct arg *args, struct sample *smp, void *private)
{
  struct buffer *trash = get_trash_chunk();

  switch (smp->data.type) {
    case SMP_T_SINT:
    {
      chunk_printf(trash, "%u", (unsigned int)smp->data.u.sint);
      break;
    }
    case SMP_T_STR:
 case_str:
    {
      struct ist validate_n = ist2(smp->data.u.str.area, smp->data.u.str.data);

      if (!istlen(validate_n))
        return 0;

      if (!(http_7239_extract_obfs(&validate_n, NULL) && !istlen(validate_n)))
        return 0; /* invalid input */
      // output with '_' prefix
      chunk_printf(trash, "_%.*s", (int)smp->data.u.str.data, smp->data.u.str.area);
      break;
    }
    default:
    {
      if (sample_casts[smp->data.type][SMP_T_STR] &&
                            sample_casts[smp->data.type][SMP_T_STR](smp))
        goto case_str;
      return 0; /* unexpected */
    }

  }

  smp->data.u.str = *trash;
  smp->data.type = SMP_T_STR;
  smp->flags &= ~SMP_F_CONST;

  return 1;

}

/* Note: must not be declared <const> as its list will be overwritten */
static struct sample_conv_kw_list sample_conv_kws = {ILH, {
  { "rfc7239_is_valid",  sample_conv_7239_valid,   0,                NULL,   SMP_T_STR,  SMP_T_BOOL},
  { "rfc7239_field",     sample_conv_7239_field,   ARG1(1,STR),      NULL,   SMP_T_STR,  SMP_T_STR},
  { "rfc7239_n2nn",      sample_conv_7239_n2nn,    0,                NULL,   SMP_T_STR,  SMP_T_ANY},
  { "rfc7239_n2np",      sample_conv_7239_n2np,    0,                NULL,   SMP_T_STR,  SMP_T_ANY},
  { "rfc7239_nn",        sample_conv_7239_nn,      0,                NULL,   SMP_T_ANY,  SMP_T_STR},
  { "rfc7239_np",        sample_conv_7239_np,      0,                NULL,   SMP_T_ANY,  SMP_T_STR},
  { NULL, NULL, 0, 0, 0 },
}};

INITCALL1(STG_REGISTER, sample_register_convs, &sample_conv_kws);

Coverage Report

Created: 2025-10-10 07:08